Up to now, woodwind instruments can generate sound by vibrating a reed installed therein, or by vibration created by airflow blown into them so that it is possible to mute or absorb the sound by controlling amplitude of such vibrations.
Among others, a recorder, one of the woodwind instruments, has an air reed comprising a window section and a wind way, and enables to generate sound by vibration created by airflow blown into it. It has been known that it is possible to mute the sound by applying a certain material to or installing an equipment at the window section, the wind way and the edge section of the recorder (Patent Literature 1).
For example, according to the Prior Art described in the Patent Literature 1, an equipment capable of generating sound without affecting the quality of the sound and adjusting the volume of sound is proposed. This equipment is to be used for the wind instruments having an air reed including recorders and able to be attached to the wind way, the window section and the edge section of such wind instruments. Particularly, the Patent Literature 1 explains that, unlike in the case of recorders, an ocarina, another wind instrument, is not cylindrical shaped and so that a belt and rubber bands for fixing are used exclusively for the ocarina in order to mute the sound by lowering the sound pressure through sliding a section capable of blocking the exhaled breath.
Further, as for brass wind instruments, an equipment attached inside of its bell has been known as equipment to mute the sound (the Patent Literature 2). According to the Prior Art described in the Patent Literature 2, as a muter to be used for woodwind instruments including recorders, an equipment to absorb sound is proposed wherein a three dimensional, net-like porous and cylindrical shaped equipment is installed inside a pipe of the body of the instrument.